During their exploration of the Arctic Circle, the team discovered a craft of unknown origin. As they investigated the crashed vehicle and its crew, later identified as Borgdrones, the members of the team were assimilated along with their ship into the Borg Collective. The new drones then attempted a journey in the Arctic One to the Collective's territory in the distant Delta Quadrant.

En route, the ship was intercepted and destroyed by the Enterprise NX-01; however, before Arctic One's destruction, the drones successfully transmitted a homing signal to the Borg, alerting them to Earth's location. (ENT: "Regeneration")

In the writer's commentary for "Regeneration" on the ENT Season 2 DVD, the episode's writers revealed that the reason the ship's mass kept growing was that the ship would have eventually evolved into a Borg sphere, implying that the Borg don't have traditional shipyards, but instead take ships they attack and assimilate them. This information wasn't conveyed in the episode, however.

Views of the model and design sketches of the ship can be found here and here.